TALKING DIRECTLY TO RYDBERG STATES

Yan Zhou, David Grimes, Ethen Klein, Timothy Barnum, Robert Field

laser mmW

MOS seminar 2014.4.22 2

Global model

Valence state (v, N)

Core-penetrating Rydberg state(v, N) = Σ(v+, N+, l)

Core-nonpenetrating Rydberg state(v+, N+, l)

laser mmW

Completely coupled Partially decoupledSeveral ion states

Completely decoupledOne ion state

PhysicsIon-core isolated from

the outside world

ChemistryStrong Ion-electron

collisionsMultichannel

collision Electron probes ion

molecular ion

Global model

JILA seminar 20140612 3

THz spectroscopy

CH3F

H2CO• Detection sensitivity is low• Multiphoton-ionization• Lack of narrow band generation (~0.1THz)• Experiment seems not to fit Rydberg molecules

* Collaborate with Prof. Keith Nelson

JILA seminar 20140612 4

Millimeter wave spectroscopy

• Initialized by Prof. Dan Kleppner• Resolution -> millimeter-wave

Unit: MHz

-60 -40 -20 0 20 40 60

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

PF

I sig

nal/a

rb.u

.

mmW detuning/MHz

5MHz

(b)

JILA seminar 20140612 5

Difficulties• Ion detection – Stray electric field – 5MHz resolution• Intensity fluctuations• Data record: (20GHz / 100kHz) x 1s = 60 hours!• Manipulations: Multi-dimensional spectroscopy, 60n hours!

Weapons• CPmmW spectrometer

• 20GHz bandwidth, 50kHz resolution• Detection efficiency improvement 10000

• Buffer gas cooling molecular beam source• Number density improvement 1000• Beam velocity improvement 10

Total improvement: 108!

Molecular system - BaF

C2Π

X2Σ+

~20100 cm-1

~18600 cm-1

IP0=38745 cm-1

n~40, ln-1, l+1

n+1, l+1v+=0, N+

D0=48200 cm-1

v+=1

v+=2

probe laser/cm-1

mill

imet

er w

ave/

GH

z

1.8455 1.846 1.8465 1.847 1.8475 1.848 1.8485

x 104

75

80

85

90

95

2 4 6 8 10 120

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8x 10

-3

mmW frequency on scope/GHz

FID

1.1 1.11 1.12 1.13 1.14 1.15

1

2

3

4

5

6

7

8

9

10

11

x 10-5

7.79 7.795 7.8 7.805 7.81 7.815 7.820

2

4

6

8

10

12

14

16

x 10-4

• 200 new transitions / hour• Laser resolution: 1 GHz• mmW resolution: 50 kHz

All people like hydrogen

All people like CNP states!

Let us go with CNP states only!

JILA seminar 20140612 8

Stark demolition

CNPCP

CP or CNP

1V/cm CNP, l>4FID

no FID

CP

2.15 2.2 2.25 2.30

0.5

1

1.5x 10

-3

2.15 2.2 2.25 2.30

0.5

1

1.5x 10

-3

8.05 8.06 8.07 8.08 8.09 8.1 8.11 8.12 8.13 8.14 8.150

2

4

6

8x 10

-4

8.05 8.06 8.07 8.08 8.09 8.1 8.11 8.12 8.13 8.14 8.150

2

4

6

8x 10

-4

CNP

CP

~10MHz

JILA seminar 20140612 9

155 160 165 170 175 180 185 190 195155

160

165

170

175

180

185

190

195

Probe laser detuning/GHz

mm

W/G

Hz

Laser forbidden CNP states

laser

mmW

mmW

laser

CP

CP

CNP

CNP-CNP transitions

CP, l=3

CNP, l=4

mmW1 mmW2

CNP, l=5

Blind search:

• A pulse sequence with 3 or more 20 GHz chirps

• Not increase the search time

mmW multiple resonances

Current work: Collecting all such CNP-CNP transitions

mmW3

CNP, l=6

JILA seminar 20140612 11

n=41 n=42 n=43 n=44

2𝑅  

𝑛3

n=42

n=43

n=44

n=45

−𝑅 /𝑛2

n=40

n=41

75-1

00 G

Hz

12 cm-1

2B 4BΔl=+1Δl=-1

Δl=-1 2B 4B

2B

JILA seminar 20140612 12

User friendly assignment recipe

• Good quantum numbers: N, parity, lR

• Pattern forming quantum numbers: N+, l• Key information: IP -> quantum defects• Tools:

• Rydberg formula , (Atom)• Selection rules: , (Polarizations) (Completely determined by

experiments)• Propensity rules: (Atom)• Reduced energy plot:

No sophisticated pattern recognition and fitting programMost information comes from experiments directly

A calculator is enough!

( , ) ( 1) ( 2 ...)rot R RE N l B N N B Nl

RRR RRQ RQR QRR RQQ QRQ QQR QQQ0

1

2

3

4

5

Tra

nsiti

on In

tens

ity

probe laser/cm-1

mill

imet

er w

ave/

GH

z

1.8455 1.846 1.8465 1.847 1.8475 1.848 1.8485

x 104

75

80

85

90

95

Organize transitions

(1) Rydberg formula (2) Up/down transitions (3) Stark demolition – CP or CNP

CPCNP

Thank you for your attention!